Government inspections uncovered 117 cases of soil contamination at former factory sites and residential areas across Japan in fiscal 1999, according to the Environment Ministry.
The cases involved soil contaminated by materials including lead, arsenic, mercury and volatile organic compounds, where toxins in the soil exceeded permissible levels stipulated by the government, ministry officials said.
Of the total, 47 cases involved trichloroethylene and 37 involved tetrachloroethylene, both of which are VOCs.
A further 30 involved lead, 23 involved arsenic and 10 involved mercury, they added.
Trichloroethylene is a colorless liquid used as a solvent in cleaning metal parts, while tetrachloroethylene is commonly used to degrease machinery. Both are highly toxic, even in small quantities.
Between 1987 and 1998, 431 contamination cases in residential areas were reported in annual joint surveys by prefectural governments and the central government.
The government took countermeasures to neutralize the soil in 390, or 90 percent, of the reported cases.
The Environment Ministry is considering stricter legislation to deal with future cases of soil contamination.
Some 169 local governments have thus far enacted ordinances or outlines to deal with soil contamination.
Current laws prohibit the contamination of rice paddies and other harvest sites, as well as laws governing contamination through dioxins.
The government is unable to prevent contamination by heavy metals and VOCs in residential areas as groundwater sources are only protected by the Water Pollution Control Law and not applicable to chemicals of this type.